The fire radical on the left tags 煤 as something burned — coal exists as a fuel, defined by combustion. It indexes 煤 with the fire family: 烧 burn, 煮 boil, 烟 smoke, 烤 roast, 炭 charcoal. Every fuel and heat-application char carries 火 or its variant 灬.
某 supplies the sound mǒu → méi, just an initial-and-tone shift. The picture of 甘 (sweet) over 木 (tree) — a sweet plum — has no semantic role here. Same phonetic series links 煤 to 媒 matchmaker, 谋 plan, 莓 berry, all sharing only their reading.
